Smooth transition dock leveler lip

ABSTRACT

A dock leveler includes a vehicle-engaging pivotal lip extending from the front end of a pivotal deck, wherein the lip has one or more unique features that provide a smooth transition for forklifts traveling between the lip and a trailer bed upon which the lip is resting. The smooth transition minimizes jolting and vibration of the forklift and its driver as the forklift wheels pass over the leading edge of the lip. The special features of the lip may include one or more of the following: a curved traffic-bearing surface terminating at a sharp or blunt leading edge, a traffic-bearing surface that includes both flat and curved sections, a multifaceted traffic-bearing surface that approximates a curved surface, a rubber or plastic shock absorbing element, an articulated nose piece at the lip&#39;s leading edge, and a main lip plate that is coplanar with the deck&#39;s traffic surface (i.e., zero crown angle).

FIELD OF THE DISCLOSURE

The subject disclosure generally pertains to dock levelers and morespecifically to a transitional lip extending from the deck of a dockleveler.

BACKGROUND OF RELATED ART

A typical loading dock of a building includes an exterior doorway withan elevated platform for loading and unloading vehicles such as trucksand trailers. Many loading docks have a dock leveler to compensate for aheight difference that may exist between the loading dock platform andan adjacent bed of a truck or trailer. A dock leveler usually includes adeck that is hinged along its back edge so that the deck can pivotallyadjust the height of its front edge to an elevation that generallymatches the height of the rear edge of the truck or trailer bed.

In addition, usually a front hinge pivotally connects an extension plateor lip to the front edge of the deck. The front hinge allows the lip topivot between a stored, pendant position and an extended, operativeposition. In the extended position, the lip can rest upon the trailerbed to form a bridge between the deck and the bed. This allows personneland material handling equipment, such as a forklift truck, to readilymove on and off the trailer during loading and unloading operations.

Often, the leading edge of the lip that rests upon the trailer bed isbeveled to create a miniature ramp that minimizes physical shock tomaterial handling equipment as their wheels travel over that leadingedge. Nonetheless, the lip's leading edge and the rest of the lip canstill jar the moving equipment and its driver. The magnitude of the joltis a function of numerous factors including, but not limited to, thelip's thickness, the geometry of the lip's leading edge, the lip-to-deckcrown angle (angle between the upper surfaces of the lip and the deck),angle between the upper surfaces of the lip and the trailer bed, heightdifferential between the trailer bed and the loading dock's elevatedplatform, the hardness and diameter of the material handling equipment'swheels, the material handling equipment's suspension, the speed of thematerial handling equipment as it passes over the lip's leading edge,the combined weight of the material handling equipment and the load itis carrying, and the suspension of the trailer being loaded or unloadedof its cargo.

Some of the shock occurring at the lip might be reduced by providing adock leveler with a crown angle that varies as a function of the deck'sangle of inclination. Such a dock leveler is disclosed in US publishedpatent application 2006/0150348A1. Although varying the crown anglemight reduce the mechanical shock caused by the height differentialbetween the truck bed and the dock's elevated platform, there are stillmany other shock-causing factors that could be addressed.

Consequently, a need exists for a better dock leveler that provides asmooth transition between the dock leveler's lip and a trailer bed uponwhich the lip is resting. Preferably, the dock leveler addresses a broadrange of often uncontrollable factors that can reduce the smoothtraveling of material handling equipment as the equipment travelsbetween the dock leveler's lip and the trailer bed.

SUMMARY

In some examples, a dock leveler lip includes a curved leading edge tosmoothen the transition between the lip and the top surface of a trailerbed.

In some examples, a dock leveler lip includes a shock absorbingpolymeric element that minimizes mechanical shock and vibration tomaterial handling equipment traveling over the lip.

In some examples, the shock absorbing polymeric element includes aninterlocking feature that helps hold the element in place.

In some examples, a dock leveler includes an articulated lip.

In some examples, a dock leveler lip includes a plurality of flat,inclined surfaces that approximate a curved surface.

In some examples, a dock leveler lip includes a combination of flat andcurved surfaces.

In some examples, a dock leveler lip includes a curved traffic-bearingsurface so that the lip can terminate at a generally sharp leading edgewithout the lip being too thin at that area of the lip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a vehicle backing toward a dock leveler whosedeck is at a stored, cross-traffic position.

FIG. 2 is a side view similar to FIG. 1 but showing the vehicle havingalready backed into the dock with the dock leveler moving into anoperating position.

FIG. 3 is a side view similar to FIG. 2 but showing the dock levelerlowering its deck upon the vehicle's trailer bed.

FIG. 4 is a side view similar to FIG. 3 but showing the dock leveler inan operative position with a forklift traveling over the lip of the dockleveler.

FIG. 5 is a side view similar to FIG. 4 but showing the dock levelerengaging a higher trailer bed.

FIG. 6 is a side view similar to FIG. 4 but showing the dock levelerengaging a lower trailer bed.

FIG. 7 is a side view a dock leveler lip according to one embodiment.

FIG. 8 is a side view of a dock leveler lip according to a secondembodiment.

FIG. 9 is a side view of a dock leveler lip according to a thirdembodiment.

FIG. 10 is a side view of a dock leveler lip according to a fourthembodiment.

FIG. 11 is a side view of a dock leveler lip according to a fifthembodiment.

FIG. 12 is a side view of a dock leveler lip according to a sixthembodiment.

FIG. 13 is a partially exploded perspective view of the dock leveler andlip of FIG. 12.

FIG. 14 is a side view of a dock leveler lip according to a seventhembodiment.

FIG. 15 is a side view similar to FIG. 14 but showing the lip engaging ahigher trailer bed.

FIG. 16 is a side view similar to FIG. 14 but showing the lip engaging alower trailer bed.

FIG. 17 is a side view similar to FIG. 14 but showing an alternateembodiment.

FIG. 18 is a side view similar to FIG. 11 but showing an alternateembodiment.

DETAILED DESCRIPTION

FIGS. 1-6 show a loading dock 10 with a dock leveler 12 for facilitatingthe loading and unloading of cargo on a trailer bed 14 or some othervehicle or truck bed. Dock leveler 12 includes a deck 16 that due to arear hinge 18 can pivot about a rear edge 20 to adjust the height of itsfront edge 22 so that trailer bed 14 and the deck's front edge 22 can beat about the same height. Deck 16 can pivot over a range of positionsincluding, but not limited to, a raised position (FIG. 2), across-traffic position (FIG. 1), and a below-dock position (FIG. 6).

To bridge the gap between the deck's front edge 22 and the rear edge oftrailer bed 14, a front hinge 24 pivotally couples a lip 26 to thedeck's front edge 22. Lip 26 can pivot between an extended position(FIG. 3) and a pendant position (FIG. 1). Together, deck 16 and lip 26provide a bridge over which a forklift 28 and other material handlingequipment can travel between trailer bed 14 and an elevated platform 30of dock 10.

As the forklift's wheels roll between trailer bed 14 and lip 26,forklift 28 and its driver may experience some jolting and vibrationbecause the upper surface of trailer bed 14 and a traffic-bearingsurface 32 of lip 26 are not perfectly coplanar. To minimize thisvibration, a leading edge 34 of lip 26 includes one or more novelfeatures that provide a smooth transition between trailer bed 14 anddeck 16. These features have been designed while carefully consideringthe typical operation of a dock leveler.

In operation, trailer bed 14 is backed into the loading dock, as shownin FIG. 1. At this point, deck 16 is at its stored, cross-trafficposition where a driveway surface 36 of deck 16 is generally flush withplatform 30, and lip 26 is at its pendant position. In some cases, edge34 of lip 26 rests upon a set of lip keepers 38 so that lip 26 can helpsupport the weight of the deck at its cross-traffic position. In caseswhere the dock leveler does not include lip keepers, a pedestalinstalled underneath the deck can be used for supporting the deck'sweight. An example of such a pedestal is disclosed in U.S. Pat. No.3,530,488.

Next, referring to FIG. 2, deck 16 rises and lip 26 swings out to extendedge 34 of lip 26 out over the top of trailer bed 14. Then, in FIG. 3,deck 16 descends to place the extended lip 26 upon trailer bed 14. Themovement of lip 26 and deck 16 can be carried out in any of a widevariety of ways that are well known to those of ordinary skill in theart. The movement, for example, can be powered, manually driven, or acombination of the two. Mechanisms for moving deck 16 or lip 26 include,but are not limited to, hydraulic cylinder or bladder, pneumaticcylinder or bladder, mechanical linkage, drive screw, rack and pinion,winch, mechanical spring, gas spring, and various combinations thereof.

Once lip 26 is resting upon trailer bed 14, as shown in FIG. 4, forklift28 can readily travel between platform 30 and trailer bed 14. The actualinclination of deck 16 and the angle between the upper surfaces of bed14 and lip 26 is partially determined based on the relative heights ofbed 14 and platform 30. FIG. 4, for instance, shows the deck'sinclination when dock leveler 12 engages a trailer bed of moderateheight, FIG. 5 shows dock leveler 12 engaging a relatively high trailerbed 14 a, and FIG. 6 shows a relatively low trailer bed 14 b. Leadingedge 34 being able to lie directly against trailer bed 14 a even thoughbed 14 a is higher than platform 30 is because the upper traffic-bearingsurfaces of lip 26 and deck 16 are at a slightly positive crown angle 40(about 5-degrees).

Although crown angle 40 ensures that the lip's leading edge 34 isresting directly upon trailer bed 14, the transition between edge 34 andbed 14 can still cause some vibration and jolting of forklift 28 and itsdriver. To minimize this vibration, a lip 26 a can be provided with asmoothly curved or contoured traffic-bearing surface 42, as shown inFIG. 7. In this example, lip 26 a has a leading edge 34 a that is asubstantially sharp line, which helps minimize any impact as a forkliftwheel rolls from trailer bed 14 onto lip 26 a. Traffic-bearing surface42, which lies between leading edge 34 a and a hinged edge 44, comprisesa first approach surface 46, a second approach surface 48, and a finalapproach surface 50.

Due to the continuous curvature of the leading portion ofbearing-surface 42, first approach surface 46 and second approachsurface 48 are at an incline relative to each other. A tangent line 52to first approach surface 46, for instance, lies at an angle (notparallel) to a line 54 that lies tangent to second approach surface 48,yet the two surfaces 46 and 48 smoothly blend due to a curved surface 56between surfaces 46 and 48. In some cases, surfaces 46, 48 and 56 havethe same radius and center of curvature.

In an alternate example, shown in FIG. 8, a lip 26 b includes a moreblunt leading edge 34 b that might be more durable than a sharp edge.Leading edge 34 b is a generally flat surface that lies at an angle(greater than zero degrees) relative to the lip's first approach surface58. In this example, lip 26 b has a traffic-bearing surface 60 thatextends between leading edge 34 b and hinged edge 44. Traffic bearingsurface 60 comprises first approach surface 58, second approach surface48, and final approach surface 50. Except for the slight differencebetween leading edges 34 a and 34 b, traffic bearing surfaces 42 and 60are substantially the same.

Because a curved surface can be more difficult to machine than a flatsurface, FIG. 9 shows an alternate lip 26 c that includes atraffic-bearing surface 62 comprising a plurality of flat surfaces,which approximate the curved surfaces of lips 26 a and 26 b. Lip 26 cincludes a leading edge 34 c similar to edge 34 b (or similar to edge 34a). Traffic-bearing surface 62 of lip 26 c extends from leading edge 34c to hinged edge 44. Surface 62 comprises a first approach surface 66, asecond approach surface 68, and final approach surface 50. Each surface66, 68 and 50 is substantially flat and lies at an incline relative tothe others.

In another example, shown in FIG. 10, a lip 26 d includes a leading edge34 d similar to edge 34 c (or similar to edge 34 a). A traffic-bearingsurface 70 of lip 26 d extends from leading edge 34 d to hinged edge 44.Traffic bearing surface 70 comprises a substantially flat first approachsurface 72, a curved second approach surface 74, and substantially flatfinal approach surface 50. Second approach surface 74 provides a smoothtangential transition between first approach surface 72 and finalapproach surface 50.

To create a more shock absorbing lip and/or to achieve a curvedtraffic-bearing surface without having to machine such a surface, a lip26 e can comprise a metal plate 76 to which a formed polymeric element78 can be attached, as shown in FIG. 11. Element 78 can be attached inany suitable manner including, but not limited to, an adhesive 80, athreaded fastener 82, a rivet, and/or a mechanically interlockingfeature (e.g., tongue-and-groove, plug-and-hole, etc.). Element 78 canbe of any desired shape. In this particular example, element 78 is of ashape that provides a traffic-bearing surface 84 that is similar tosurface 60 of FIG. 8. Element 78 can also be of any desired material,including but not limited to, neoprene rubber or polyurethane. Anysuitable manufacturing process including, but not limited to, extrusion,plastic injection molding, and machining can produce element 78. Element78 can be one continuous piece that extends the full width of deck 16,or element 78 can comprises a plurality of segments. The phantom linesof FIG. 11 illustrate the flexure of element 78 as a strong lower edge83 of lip 26 e rests firmly upon trailer bed 14. In addition toflexibility, element 78 may advantageously have shock or vibrationabsorption or dampening properties. Such properties would serve tominimize or eliminate vibration transmitted from the leveler to theforktruck operator resulting from contact therebetween and/or movementof the forktruck over the leveler, or at least the lip.

When a formed polymeric element or insert is used, the leading edge ofthe lip might be more durable if the underlying metal plate of the lipextends all the way to the tip of the lip. FIGS. 12 and 13, for example,show a lip 26 f comprising a formed polymeric element 86 attached to ametal plate 88. Plate 88 extends fully to a leading edge 34 f of lip 26f so that the strength of edge 34 f is sufficient to support the weightof deck 16 when lip 26 f is in its pendant position held by lip keepers38 (FIG. 1). Element 86 can be comprised of a series of segments 90,which might make lip 26 f easier to manufacture, ship and assemble.Moreover, worn segments could be replaced with new ones or theirpositions could be interchanged as some segments 90 in high trafficareas wear faster than others. Although element 86 could be attached inany suitable manner, such as those mentioned with reference to element78 of FIG. 11, each segment 90 could include a plurality of plugs 92that press-fit into a corresponding plurality of holes 94 in plate 88.

In another embodiment, shown in FIGS. 14, 15 and 16, an articulated lipassembly 26 g comprises a metal or polymeric nose piece 98 that ispivotally attached to a metal plate 100 (main piece). A hinge 102 orpivotal connection between nose piece 98 and plate 100 allows piece 98to lie generally flat against trailer bed 14 regardless of whether thetrailer bed's elevation is high as shown in FIG. 15, low as shown inFIG. 16, or at an intermediate elevation as shown in FIG. 14. FIGS. 14,15 and 16 generally correspond to FIGS. 4, 5 and 6 respectively. In thisexample, lip 26 g includes a generally sharp leading edge 34 g, and atraffic-bearing surface 96 extends between leading edge 34 g and hingededge 44. Although edge 34 g is shown as a sharp edge, leading edge 34 gcould by of any shape including, but not limited to the shapesillustrated in FIGS. 7-13. Nose piece 98 can be one continuous piecethat extends most of the full width of deck 16, or piece 98 cancomprises two or more segments (plurality of leading edge pieces) thatare distributed along plate 100 in a manner similar to the distributionof segments 90 of FIG. 13.

In some examples, as shown in FIG. 17, an articulated lip assembly 26 hcomprises nose piece 98, an intermediate link 104, and a main piece 106.The articulation of assembly 26 h allows a leading edge 108 of nosepiece 98 to rest upon trailer bed 14 even when bed 14 is higher thandeck 16. Unlike many other dock levelers, this design does not require acrown angle where main piece 106 abuts the front edge of deck 16 (seecrown angle 110 of FIG. 4). Instead, a main traffic surface 112 of mainpiece 106 is substantially coplanar with deck traffic surface 36 of deck16. This is a significant advantage because crown angles can bedifficult to produce and maintain.

Alternatively, FIG. 18 shows a lip assembly 26 k where the articulatedportion of assembly 26 h of FIG. 17 is basically replaced by a flexibleleading edge piece 114 similar to element 78 of FIG. 11. When trailerbed 14 is higher than deck 16, as shown in FIG. 18, a relatively stiffmain piece 116 can rest solidly upon bed 14, while a wheel 118 from aforklift or other type of material handling equipment can deflectleading edge piece 114 down against bed 14, thereby providing wheel 118with a generally smooth path to travel between bed 14 and deck 16.Again, this design does not require a crown angle where main piece 116abuts the front edge of deck 16, thus a main traffic surface 120 of mainpiece 116 can be substantially coplanar with deck traffic surface 36 ofdeck 16.

It should be noted that leading edge piece 114 (FIG. 18), nose piece 98(FIG. 17), and element 90 (FIG. 12) are all deflectively coupled to amain piece. The term, “deflectively coupled” refers to a connectionbetween two pieces where some localized or total relative movement canoccur between the two. Examples of such movement include, but are notlimited to, resilient bending, resilient deformation, resilientlocalized compression, and pivotal movement.

Although the invention is described with respect to various examples,modifications thereto will be apparent to those of ordinary skill in theart. The scope of the invention, therefore, is to be determined byreference to the following claims.

1. A dock leveler, comprising: a deck that includes a front edge and arear edge, the deck is pivotal about the rear edge to selectively raiseand lower the front edge; and a lip that includes a leading edge, ahinged edge and a traffic-bearing surface extending therebetween, thehinged edge is pivotally coupled to the front edge of the deck such thatthe leading edge can selectively rise and descend relative to the frontedge of the deck, the traffic-bearing surface includes a first approachsurface, a second approach surface and a final approach surface suchthat: a) the first approach surface is adjacent to the leading edge ofthe lip; b) the first approach surface is between the leading edge ofthe lip and the second approach surface; and c) the final approachsurface is adjacent to the hinged edge of the lip, and the finalapproach surface is between the second approach surface and the hingededge, wherein each of the first approach surface, the second approachsurface and the final approach surface are at an incline relative toeach other.
 2. The dock leveler of claim 1, wherein each of the firstapproach surface, the second approach surface and the final approachsurface are substantially flat.
 3. The dock leveler of claim 1, whereinat least one of the first approach surface and the second approachsurface is curved.
 4. The dock leveler of claim 1, wherein a curvedsurface exists between the first approach surface and the secondapproach surface.
 5. The dock leveler of claim 1, wherein a curvedsurface exists between the second approach surface and the finalapproach surface.
 6. The dock leveler of claim 1, wherein the leadingedge provides a generally flat surface that lies at an angle greaterthan zero degrees relative to the first approach surface.
 7. The dockleveler of claim 1, wherein the leading edge is a substantially sharpline.
 8. The dock leveler of claim 1, wherein the traffic-bearingsurface includes a polymeric element carried by the lip.
 9. The dockleveler of claim 8, wherein the polymeric element includes the leadingedge of the lip.
 10. The dock leveler of claim 8, wherein the polymericelement is between the leading edge and the final approach surface. 11.The dock leveler of claim 8, wherein the polymeric element includes acurved surface.
 12. A dock leveler comprising: a deck that includes afront edge and a rear edge, the deck is pivotal about the rear edge toselectively raise and lower the front edge; and a lip that includes aleading edge, a hinged edge and a traffic-bearing surface extendingtherebetween, the hinged edge is pivotally coupled to the front edge ofthe deck such that the leading edge can move vertically relative to thefront edge of the deck, the traffic-bearing surface includes a curvedsurface.
 13. The dock leveler of claim 12, wherein the leading edgeprovides a generally flat surface that lies at an angle greater thanzero degrees relative to the curved surface.
 14. The dock leveler ofclaim 12, wherein the leading edge is a substantially sharp line. 15.The dock leveler of claim 12, wherein the traffic-bearing surfaceincludes a polymeric element carried by the lip.
 16. The dock leveler ofclaim 15, wherein the polymeric element extends to the leading edge ofthe lip.
 17. A dock leveler comprising: a deck that includes a frontedge and a rear edge, the deck is pivotal about the rear edge toselectively raise and lower the front edge; and a lip assemblycomprising a main piece and a leading edge piece, the main piece ispivotally coupled to the front edge of the deck, the leading edge pieceis defectively coupled to the main piece.
 18. The dock leveler of claim17, wherein the main piece is between the leading edge piece and thefront edge of the deck.
 19. The dock leveler of claim 17, wherein theleading edge piece includes a leading edge that is generally a sharpstraight line, the leading edge is a portion of the leading edge piecethat is farthest away from the main piece of the lip assembly.
 20. Thedock leveler of claim 17, further comprising a first hinge at the rearedge of the deck, a second hinge at the front edge of the deck, and athird hinge between the leading edge piece and the main piece of the lipassembly.
 21. The dock leveler of claim 17, wherein the leading edgepiece extends substantially a full length along the front edge.
 22. Thedock leveler of claim 17, wherein the lip assembly includes a pluralityof leading edge pieces that are distributed along the main piece. 23.The dock leveler of claim 17, wherein the leading edge piece is at leastpartially comprised of a polymeric material.
 24. The dock leveler ofclaim 17, wherein the leading edge piece includes a curved surface. 25.The dock leveler of claim 17, further comprising an adhesive that bondsthe leading edge piece to the main piece.
 26. The dock leveler of claim17, further comprising a fastener that holds the leading edge piece inplace.
 27. The dock leveler of claim 17, wherein the leading edge pieceincludes an interlocking feature that helps hold the leading edge piecein place.
 28. The dock leveler of claim 17, wherein the main piece has amain traffic surface, the deck has a deck traffic surface, and the mainpiece can pivot to a position where the main traffic surface and thedeck traffic surface are substantially coplanar.
 29. A dock levelercomprising: a deck that includes a front edge and a rear edge, the deckis pivotal about the rear edge to selectively raise and lower the frontedge; a lip that includes a leading edge, a hinged portion and atraffic-bearing surface extending therebetween, the hinged portion ispivotally coupled to the front edge of the deck such that the leadingedge can move vertically relative to the front edge of the deck; and apolymeric piece that provides a least a portion of the traffic bearingsurface.
 30. A dock leveler comprising: a deck that includes a frontedge and a rear edge, the deck is pivotal about the rear edge toselectively raise and lower the front edge; and a lip assemblycomprising a main piece and a leading edge piece, the main piece ispivotally coupled to the front edge of the deck, the leading edge pieceis pivotally coupled to the main piece such that the main piece isbetween the leading edge piece and the front edge of the deck.